8. Mix hydrogen peroxide with pure water to give the following percentage of concentration of acid: 100%, 80%, 60%, 40% and 20% 9. Repeat 1 8 using the 100%, 80%, 60%, 40% and 20% hydrogen peroxide 10. Repeat the whole experiment three times to get a more reliable result 11. Plot graphs for each concentration -volume of gas collected against time 12. Draw best-fit lines Diagram Analysis After I have done the experiment, I have got the results: 1st result Time (Seconds) Volume of gas collected when there is 100% of H O (cm ).
Volume of gas collected when there is 80% of H O (cm ) Volume of gas collected when there is 20% of H O (cm ) 1. 5 2. 6 3. 7 5. 0 6. 2 7. 5 8. 6 9. 6 Now I am going to draw the graphs volume of gas collected against time. The graphs shows a curve best-fit line that means whenever the concentration increases, the volume of gas that was collected in the given time increases but the volume of gas collected increase at a slower rate at the end. The 100% concentration produced the most oxygen in the shortest time, which gives it a higher reaction rate than the others.
According to the graph, it has proven my prediction is correct. The highest concentration would produce the most oxygen in the shortest time. The volume of gas collected increases at a slower rate at the end because the towards the end, there are less substrate and enzyme left, so it takes longer to react and releases the gas(oxygen). The rate of reaction is a measure of how fast the reaction takes place. A reaction will take place when the particles of the reacting substances collide with each other and a fixed amount of energy called the activation energy is reached.
If a collision between particles can produce sufficient energy (i. e. if they collide fast enough and in the right direction) a reaction will take place. This is called the Collision Theory for rates of reaction. Concentration of the substrate increases, the greater the rate of reaction will be because higher concentration means a higher number of particles in a given volume. If there are more particles, there will be more reaction. More reaction means a larger number of successful collisions. Therefore the catalase action rate will increase. Also, the particles are closer together, so they can collide more often.
The more often they collide, the chance of reaction happening increases. So the catalase action rate increases. Evaluation I think the results are very good that I can use them to support what I predicted at the beginning. I also have enough evidence to support my conclusion. The points on my graph are not very close to the best-fit line which is due to the large scale I used, so the gap seems to be bigger. But the points let me draw reasonable best-fit lines and they also show the pattern I expect. I think I can still rely on the results because they show the general pattern for each concentration.
I know my results are reliable because they fitted my prediction and it also enables me to explain the relation between concentration and rate of catalase reaction. Also, I repeated my experiment three times to obtain the results, so I know they are reliable. The appropriate apparatus I used, increases the accuracy of the results. I think my experiment is quite successful as I can collect results that help me to draw some accurate graphs except there are a few anomalous points. I think this happened because: 1) I did not close the bung quick enough and some gas leak out which cause a decrease in the readings
2) I did not use the same celery each time because 1 celery does not provide sufficient catalase for the whole experiment which can cause increase or decrease to the readings 3) The temperature is slightly different as I did the experiment in three different days which can cause increase or decrease to the readings I think there is a better way of doing it that is to have a tap at the top. When I open it, the hydrogen peroxide will drop down into the catalase and I do not need to put the bung on because the bung is put on top of the tap which means no gas will leak out.
Also, when I time it with a stopwatch, it will not be as accurate as using computers to time because human has reaction time that will increase the time taken and this will make the experiment less accurate. I can do the experiment in this way: For this experiment, I have used celery as a source of catalase, other than this; I can use potatoes or liver that may affect the time taken to collect gas, as they are different. Further experiment Planning Apparatus A 50cm conical flask with a bung A burette Clamps and stand Delivery tube Container 10cm measuring cylinder A stopwatch.
20 vol of hydrogen peroxide Potato tubes (catalase) Safety control I have to make sure all the school bags and chairs are under the table, in case I trip over I have to wear goggles, prevent any accidents that can damage my eyes I have to make sure I handle all the glassware carefully I have to handle the hydrogen peroxide very carefully because it is very toxic Method 1. Set up the experiment according to the diagram 2. Measure 10 g of catalase (potato juice) 3.
Measure 10 cm of Hydrogen Peroxide 4. Pour the catalase into the conical flask 5. Fill the burette with water 6.Set up the light sensor and the computer 7. Turn on the tap and start the computer at the same time 8. Record the volume of gas given off every 10 seconds (10s, 20s, 30s, 40s, 50s, 60s, 70s and 80s) 9. Mix hydrogen peroxide with pure water to give the following percentage of concentration of acid: 100%, 80%, 60%, 40% and 20% 10. Repeat 1 9 using the 100%, 80%, 60%, 40% and 20% hydrogen peroxide 11. Repeat the whole experiment three times to get a more accurate result 12. Plot graphs for different concentration- volume of gas collected against time 13. Draw best-fit lines 14.